Fuel air ratio instrument



Oct. 24, 1950 c,.w CQCHRAN, JR 2,526,635

FUEL AIR RATIO INSTRUMENT Filed Nov 14, 1945 5 w 23 22 COMPENSATED l5 FUEL VENTURI SUCTION lMPACT PRESSURE 6 INLET W I j a 2| FUEL.

OUTLET FIG. 4. I FIG. 2.

/ CARBURETOR VENTURI VENTURI SUCTION PRESSURE COM PENSATED 25" 58 IMPACT PRESSURE FUEL INLET INVENTOR.

I FUEL OUTLET TO ENGINE FIG. 3,

ATTORN EY.

CHARLES w COCHRANJR Patented Oct. 24, 1 950 1 Charles W: Cochran, Jr., Unitedstates Navy,

' 'Yeadon; Pa.

Applicatiorioveinber 14, 1945', Serial No. 628,626

(Grantd under the act of March 3, 1883, as

' 2 Claims.

' This invention is basicallya novel fuel-air ra'tio instrument intended toinaintain and'indicatethe fuel-air ratio of internalcombustion engines. It can, however, also be used for "fluid" fuel'an'd air ratio control of heating units such as oil burn-v i ing heaters, furnaces, ovens, etc. A further use awouldbe as a fluid ratio control and indicator in,

the chemical'industr-yl Althou'gh fuel and air as supplied to an internal' combustion engine are use'dherein as an example it is understood that any otherdesired fluids maybeso controlled and indicated for otherpurposes and processes.

The operation of this instrument is based on the: 7 pressure drop resulting -vvhen i a fluid flows through an orifice. TThis fiow and pressure drop varyaccording to the relative pressure and'viscosamended April 30, 1928; 370 0. G. '757) ity of the fluids. Byi using a'fix'ed orifice'for one fluid alldia variable orifice for the other the pressure relationship between these fluids can be maintained; therefore, the fluid' flow ratio is proportionate: toxthe:area of 'the-variable orifice. In Jthisinvention the area of: the second orifice is varied bymeansof a poppet valve, thus lthe'position of thepopp'et indicates the orifice areaj' and. the fluid. ratio.

Furthermore, an instrum'ent' of this type can be used to calibrate the carburetors of existing automotive enginesjarid-so adjust them for 'most'efficient operation. This wouldbe' particularly-useful :in'automobile1i' service 'stations and airfield shops. I

Be'ing .a self 'contained unitthis instrument permits, by means of regular tubing connections, of installation on eXisting'aircra-ft engines. This would regulate their operation, increase their,

power efficiency byimproved combustion and fuel economy, and consequently maintain them in 'cleaneropera ting condition and for longer periods between overhauls. 1

These and-'ib'theriobjectsof this' invention will becomemore apparent from the following detailed description and the accompanyingsdrawingwhich 1 illustrates a typical embodiment of this invention. vLin the drawing: f

Fig.- 1 is a longitudinal section" view showing all the} internal parts "of "the operating mechanism, the indicating mechanism actuating device; and the piping connections. I Y 7 igJ-Z is an outer end view indicating thecylind rical shape. of the device, .anclitsassembly bolts.

Fig. 3 is a'diagrammatic View illustrating typical installation connections-between the indicator, transmitter and carburetor. v

-Eigg 4 -is a face view showing the graduations on a typical indicating instrument dial.

Referring now to Fig. 1-, it is seen that the principal'components of-thisinvention are amultisection outer case i 2, l3, l, 59"divided into chainbers 75, 9, i0, i6, W, i8, 23; 36 by partitions 31 318 and-oliaphragms l," 2, 3; 4; a'valve'stem 5fiand a poppet valve !9. The fuel enters throughsup'ply connection 55 into fchamber aridythen 'into annular duct i i from wh'ichits furthefflow through port 253 is restricted by the movements ofthe'pop- "pet valve it. However, fuel at maximumpressure entering'thr'ough by-pass 6 into chamber l1 builds up a difierential pressure under diaphragm l which tends to holdthe poppet 'valve' 19 open. The fuel in chamber'lfi is at lower pressure and is free to flow'out to the carburetor through discharge connection 2!. Due to communicating by-pass"8, the pressure in chamber il is the same as in chamber 56 and-diaphragms 3 and 4 balance each other approximately. .All diaphragms act as seals between chambers.

Thepressure through connection 22 in chamber IB is 'the total or impact pressure of the other pressure through connection 23 in chamber 20 is thesuctioncr static pressure in the orifice25. Therefore; thepressure difierential on diaphragm 2 tends to. close the poppet valve I9.

The pressuresin chambers l 0 and I 6- are equalized through ports B0, thus preventing excessive dash pot effect. 1

-As diaphragm 4 is ba'lancedby diaphragm 3 and poppet valve I9 is balanced through port" 60, then the only forces tending to open or close-the 'poppet valve [9 are the pressure differentials across diaphragms I andZ. These differentials Will operate the poppet valve l9 so as to balance diaphragm l' against diaphragm 2. l The operation or the diaphragms l, Z,' '-3, 4-; is transmitted to the poppet valve "l9 by'a' co-airial floating shaft: 5. =The'diaphr'agms |;-2, 3, 4,a re

securelyheld to-the shaft-'5 andproperlvspaced b emeans of cylindrical 'spacers"24,'*2B',"21-, 28, Washer Mand nut'im. The large" diaphragmsf'l and 2 are backedup with retainer plates fi 33'.

The large diaphragms l and 'z are clampedegears 41 42.. fBy mean'sof quadrant slot fl diaphragms 3"and-4 are secured by flat and" machine screws 35.

In chamber 36 secured to partition 38'b'y screws 39 i is a commercial electrical autosyn' position transmitter 4!) butother equivalent means can be used-instead. The movementsof the poppet valve l ware conveyed to transmitter iil by shaft 5' and by means of linkage parts 43, M, 45, 46, AT

maintain a fuel-air ratio.

across diaphragm 2.

gravitation.

turnbuckle 43 it is possible to make any required adjustments to get the initial reading on the commercial indicator 49 which has a specially graduated dial 50. These adjustments permit the same instrument to be used for various sizes of fixed orifices and various dial graduations.

The electric autosyn position transmitter 40 (equivalent to Pioneer #AY-SH) has regular electric wiring connections 5! through opening 55 to commercial position indicator 49.

The Venturi suction pressure line 58 connects from the carburetor Venturi 25 to chamber 20.

The air impact pressure line 52 connects from center of carburetor Venturi 25 as shown to chamber l8. It is provided with a Sylphon type compensating unit 53, which is necessary where a compressible fluid, such as air, is involved. This compensator is a type of pressure and temperature compensating device which is a part of the standard carburetor equipment. It forms no part of this invention. It comprises a two interconnected chambered device, one the impact chamber and the other containing a bellows filled with a combination of a liquid and a vapor. The combination is sensitive to fluctuations in pressure and temperature, and causes the bellows to expand or contract with these fluctuations. The bellows operates a stem bleed valve from the impact chamber to the atmosphere By proper adjustment this compensator compensates the impact air pressure so that air flow by Weight is indicated rather than volume flow.

All diaphragms have one or more corrugations 54 to permit free movements.

A removable plate 59 covers the transmitter chamber 36.

' Suitable sealing gaskets 56 will be provided at all section connections. Through bolts 51, tie all sections l2, l3, I4, 59, together.

In operation this instrument does not set or 7 It indicates fuelair ratio. The metering suction pressure differential across the Venturi of the carburetor of an aircraft engine is constantly changing because of fluctuation in air currents, plane speed,'throttle setting, etc. Therefore, the pressure differential across diaphragm 2 is always fluctuating and ,moving valve [9 back and forth, always maintaining the fuel pressure diiferential across diaphragm l equal to the air pressure differential Variation in fuel pressure does not affect this reading as fuel-pressure differential is used.

The design permits of manufacture in any size desired, to any practical pressure requirements, and of materials suitable for the fluids controlled. Furthermore, the operation is not affected by changes in inclination, vehicle motions or by It is equally suitable for operational use on planes and test service on automotive engines. Being fully automatic within its adjustment range it will function dependably at the selected setting, requiring no further manual operation.

From the foregoing description it will be apparent that the present invention provides a novel and improved means of ratio control and indication for fluids such as air and automotive fuels, chemical fluid mixtures, and liquid fuels for heating and general industrial use. The device being entirely foolproof, can be adjusted by experienced personnel and then used automaticalilzy or by unskilled labor with equally good resu s.

Furthermore, the invention provides a novel device with the described features and operating characteristics and of a durable design and substantially easy and inexpensive to manufacture.

While a particular embodiment of the present invention has been shown and described herein, it is not intended to limit the invention to such disclosure, and changes and modifications may be made therein and thereto within the scope of the claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

I claim:

1. Apparatus for indicating the proportional delivery of fluids in two fluid lines, comprising a casing, first and second aligned compartments in said casing, a diaphragm in each compartment dividing it into two adjoining chambers, means connected to said diaphragms for movement as a unit, a single admission valve for said second compartment having connection to one Of said fluid lines, said valve being mechanically connected to said means and movable therewith to open and closed positions, both chambers of said second compartment adjoining said valve being connected by passage ways to the inlet side of said valve, ports connecting each of the chambers in said first compartment to differential pressure points in the other of said fluid lines, and means responsive to the displacement of said valve, to indicate a ratio of the flow of said fluid.

2. Apparatus for indicating the proportional delivery of fluids in two fluid lines, comprising a casing, first and second aligned compartments in said casing, a main diaphragm in each compartment dividing it into two adjoining chambers, a single admission valve for said second compartment having connection to one of said fluid lines, a movable element attached to each of said main diaphragms and said valve, support .diaphragms mounted in the compartment walls for supporting said element for movement whereby said valve is adjusted to open and closed positions, both chambers of said second compartment adjoining said valve being connected by passageways to the inlet side of said valve, ports connecting each of the chambers in said first compartment to differential points in the other of said fluid lines, and means responsive to the displacement of said valve to indicate a ratio of flow of said fluid.

CHARLES W. COCHRAN, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,308,626 Crowell July 1, 1919 1,333,986 Lundgaard Mar. 16, 1920 1,363,513 Keith Dec. 28, 1920 1,9 1,145 Albright Aug. 8, 1933 2,074,882 Wunsch Mar. 23, 1937 2,143,820 Payn Jan. 10, 1939 2,217,641 Junkins Oct. 8, 1940 2,217,642 Luhrs Oct. 8, 1940 2,382,625 Garretson Aug. 14, 1945 FOREIGN PATENTS Number Country Date 490,607 Great Britain Aug. 1'7, 1938 

